1. Field of the Invention
The present invention generally relates to a method for protecting the backside of a wafer in process of transferring for IC manufacturers. In particular, the present invention relates to a method for protecting the backside of a wafer with micro-electro-mechanical systems (MEMS) thereon.
2. Description of the Prior Art
In common IC fabrications (fabs), the front-side or topside of a wafer is mainly concerned due to all IC devices and elements constructed on the topside of the wafer. Thereof the wafer uses to be delivered with touching of backside of wafer transfer systems, for example, robot, picker and etc. In another word, the process of fabricating IC will be continued even if the backside of the wafer is scratched slightly by an operator and wafer transfer systems. But it is necessary that there is no breakdown of the wafer due to scratches even though after high temperature process, and damage the IC devices on and within the wafer.
Oppositely, both topside and backside of a MEMS (micro-electro-mechanical systems) wafer are concerned on application. There may be IC devices, micro-electro elements or micro-mechanical elements on the both sides on a MEMS wafer. On other applications, there may be other devices assembled with the backside of the MEMS wafer, such as ink jet print-head chips of the MEMS wafer. Accordingly, the backside of the MEMS wafer should be regarded as important as the topside of the MEMS wafer. Unfortunately, the most of transfer wafer systems in IC fabs are in touch with the backside of MEMS wafers when delivering MEMS wafers as well as those general wafers, so as to result in the damage or scratch on the backside of MEMS wafer. The damaged and scratched MEMS wafers make process of fabricating MEMS fail then the wafers must to be scraped. There is much lost of throughput and yield rate of MEMS products due to these issues.